When Terry Boston, who has died aged 81, contested a byelection in Faversham, Kent, in June 1964, defending one of the smallest Labour majorities in the country, a general election was on the horizon. The party heralded his victory as a helpful portent of the approaching contest, which four months later would bring Harold Wilson to power as prime minister. Boston's role emerged firstly as a helpful backroom figure to his party, then similarly useful later in the House of Lords, as chairman of committees and deputy speaker. Despite sitting in parliament almost continuously for more than 40 years, he served only briefly in government, as a junior whip in 1969-70, and as a Home Office minister in 1979.

Boston read law at King's College London and worked as a broadcast journalist before he entered the Commons. His experience at the BBC attracted the attention of Wilson, whom he then served as a media adviser. He was a trusted member of the inner circle at Downing Street at the time of the 1974 general elections, when he was in charge of organising press conferences – along with Wilson's bags and baggage – and he ran James Callaghan's political office at No 10 during the 1979 election. He was a popular, genial figure who provided a much-needed calming influence within the Wilson entourage, and was renowned for his frequent exclamations of "Well, I'll be blessed!" and "Bless my soul!" which led to him being dubbed "the Blessed Boston" by the No 10 press secretary Joe Haines.

The son of a civil servant, George Thomas Boston, and his wife, Kate Bellati, Terry attended Woolwich Polytechnic school, south-east London, and joined the Labour party at the age of 16. He was an enthusiastic member of the Labour League of Youth and a member of the world executive committee of the International Union of Socialist Youth. He was also a member of the national committee of the Council for Education in World Citizenship in 1950, an interest he pursued later when he was the UK delegate to three sessions of the UN general assembly (1976-78).

Boston was commissioned in the RAF during national service (1950-52) and trained as a pilot with the University of London Air Squadron. Called to the bar in 1960, he had already joined the BBC in 1957 as a subeditor on external services. He was a current affairs producer for four years before winning his seat, and used his legal expertise as the producer of the Law in Action series. He maintained an interest in broadcasting as a Lords member of the Parliamentary Broadcasting Unit (1994-2000), and in 1980 he chaired the consortium that won the franchise to broadcast the new independent TV station for the south of England, TVS.

He stood first for the Commons as the Labour candidate in the Conservative seat of Wokingham, Berkshire, in the 1955 and 1959 general elections, and then came to the attention of the Labour MP for Faversham, Percy Wells, who wanted Boston to succeed him at the 1964 election.

After Wells's death in April 1964 and a Labour defeat at a byelection in Devizes, the prospects for Boston's election at marginal Faversham (1959 majority 253) did not look good. Wilson led the list of party bigwigs campaigning in a desperate attempt to win the seat, which on the day Boston secured easily with a majority of nearly 4,000.

At the time Faversham was regarded as the best organised constituency in the country, with 5,000 individual party members and eight Labour halls. Boston was a diligent constituency MP, always on his feet in the Commons pursuing the interests of the dockyard workers on the Thames estuary and the farmworkers in the Kent orchards, and seeking to prevent the siting of the third London airport in the vicinity. However, the profile of the area changed rapidly, and his defeat to the Conservative Roger Moate in 1970 was widely predicted. He maintained an interest in the area, as a trustee of Leeds Castle until 2010.

He had been made an early bag carrier in the Commons as a parliamentary private secretary from 1964. Two years later, he became PPS to another alumnus of Woolwich Polytechnic, Richard Marsh at the Ministry of Power, and followed him to the Ministry of Transport (1968‑69). He was elevated to the Lords in Wilson's resignation honours list in 1976, being one of the few uncontroversial names on the notorious "Lavender list". In 1979 Callaghan appointed him Home Office minister with responsibility for prisons, but it was to be a short-lived ministerial career with the "Crisis? What crisis?" election imminent.

Boston served as opposition spokesman on home affairs (1979-84) and on defence (1984-86). He was chairman of committees (1994-2000) and deputy speaker (1991-2008). He sat on the woolsack for the debate that led to the abolition of hereditary peers in 1999 and won praise for the manner in which he handled the difficult vote during which the Earl of Burford threw himself at the woolsack. Lady Wilson (Wilson's widow, Mary) congratulated him later on how, with a subtle nod to the ushers, he had secured the removal of the indignant earl.

He married an Australian-born market research consultant, Margaret Head, in 1962. She survives him.

• Terence George Boston, Lord Boston of Faversham, politician, lawyer and broadcaster, born 21 March 1930; died 23 July 2011